Inorganic peroxidic bleaches activated with n,n&#39;-diacyl-methylene-diformamide



United States Patent US. Cl. 8-111 Int. Cl. D06] 3/00 5 Claims ABSTRACT OF THE DISCLOSURE Bleaching of textile fibers with an aqueous peroxidic bath activated with an N,N'-diacyl-methylene-diformamide of the formula wherein R and R are carboxylic acid acyl groups having 1-12 carbon atoms.

The present invention relates to an improved process for the treatment of natural and synthetic textile fibers, either as such or in the form of yarns, woven and knitted fabrics or articles produced therefrom, with aqueous baths containing peroxidic bleaching compounds and more particularly with such baths containing novel activators and stable solid compositions suitable for the preparation of such activated baths.

It is known that peroxidic compounds, such as, hydrogen peroxide, sodium peroxide, sodium perborate, sodium percarbonate, sodium perphosphate and the like, can be used in washing and bleaching baths for textile fibers of all types. However, as a rule, when the textile fibers concerned are plant fibers, such as, cotton or linen, the goods to be treated are introduced into the washing and bleaching bath containing the usual washing agents, such as, soaps or synthetic detergents, as well as alkalies, water glass, phosphates and peroxidic compounds at room or moderately raised temperatures and then slowly heated up to about the boiling point and kept at such high temperature for some time. This boil wash is not only cumbersome and expensive but also when the goods treated contain sensitive fibers, such as, artificial silk, rayon staple fibers or fully synthetic fibers, can lead to fiber damage. As a consequence, attempts have been made to carry out the treatment at temperatures below the boiling temperature but such attempts have not always led to satisfactory results. It was found that the optimum cleaning elfect of the usual washing compositions on cellulose fibers is only attained at temperatures near the boiling point so that when lower temperatures are employed an insuflicient cleaning effect is attained. When the so-called self-acting washing agents, which, as is known, contain peroxidic compounds such as sodium perborate, are employed at lower temperatures, such as, for example, 60 to 70 C., an insufiicient bleaching action is obtained as the stability of the usual commercial perborate compositions is so adjusted that they give oif their active oxygen to the fiber with sufiicient rapidity only at high temperatures.

As a consequence, proposals have been made to activate the peroxidic bleaching compositions so that they are effective when used at temperatures below 90 C., such as, for example, 60 to 70 C. For example, amides of unsaturated carboxylic acids, such as, acrylic acid or methacrylic acid as well as their low molecular weight polymers have been used as activators in conjunction with such bleaching compositions. In addition, amides of saturated acids carrying solubility promoting substituents, for instance, hydroxy groups on the amido group, such as, for example, can be obtained from monoor diethanol amine have been used for the same purpose. Other suggested amides for this purpose are acetyl amides, benzoyl amides and formamide. It was found that in many instances the suggested amides do not provide sufiicient activating action or that upon storage, especially in contact with the atmosphere, they have a tendency to split off the acid, particularly when the individual nitrogen atoms carry more than one acyl group. This undesired acid cleavage renders the addition of such amides to finished washing composition containing active oxygen undesirable as upon storage of such compositions it causes reactions which reduce the effectiveness of such compositions when they are ultimately used in washing and bleaching baths.

It therefore is an object of the present invention to provide a way of activating peroxidic bleaching agents to a greater extent while at the same time increasing the stability on storage of the dry activated compositions.

According to the invention it was found that this object could be attained when derivatives of methylenediformamide are employed as the activator. The methylene-diformamide derivatives which come into consideration are of the following formula:

wherein R and R are carboxylic acid acyl groups containing 1 to 12 carbon atoms. N,N'-dibenzoyl-methylenediformamide, N,N' dipropionyl-methylenediformamide and N,N'-diacetyl-methylene-diformamide come into question.

It was found that such methylene-diformamide derivatives react briskly with hydrogen peroxide or other active oxygen carriers, such as, sodium perborate, sodium percorbonate and the like, when dissolved in water at moderately raised temperatures, such as, for example, 60 to 70 C., with simultaneous increase in the bleaching action of such active oxygen carriers. They, on the other hand, do not have the tendency to split off the acids of the acyl groups upon storage. The high activating action as well as the better stability are both still evident even when longer chained aliphatic acyl groups are present on the nitrogen atoms in addition to the formyl groups.

N,N-d-iacetyl-methylene-diformamide of the formula:

has proved particularly satisfactory for the purposes of the invention as it is very reactive but, on the other hand, also is stable and does not split off acetic acid upon storage in contact with the atmosphere.

It was found that the methylene-diformamide derivatives in question which contain two nitrogen atoms and an additional acyl group besides the formyl group on each nitrogen atom possess a stability on storage and activating action on peroxidic bleaching agents which is not possessed when such additional acyl group is absent or when a compound containing only one nitrogen group is concerned.

The activator employed according to the invention can be mixed in with the washing and bleaching composition during the production of such mixture or later. Such activator also may be added directly to the washing and N,N-dlpr0p10nyl-methylenediformamlde is as efiectlve as the just mentioned compound.

3 bleaching bath. The quantities of the activators required amounts to about 0.3 to 2 mols of the activator per mol of active oxygen in the washing and bleaching composition.

The activating action occurs in neutral, weakly acidic or weakly alkaline baths or, in other words, at a pH between about 3 and 11. The active oxygen content of the baths preferably is between about 0.05 g. and 20 g. per liter. The usual stabilizers, buffers, wetting agents, detergent protective agents for textil fibers, and/or optical brighteners employed in washing and bleaching compositions can also be present in the compositions or baths according to the invention.

The mixtures of solid inorganic peroxidic bleaching agents and the methylene-diformamide derivatives according to the invention as well as their mixtures with the other usual washing agents are stable on storage at normal temperature in contact with the atmosphere and they therefore can be stored in a form ready for use in the preparation of aqueous activated bleaching baths.

The extraordinarily low cost of the production of the starting material methylene-diformamide (from formamide and formaldehyde) for the preparation of the activators according to the invention is of special significance as the cost factor is especially important in washing and bleaching compositions which are products produced in great volume.

The following examples will serve to illustrate the invention.

EXAMPLE 1 Production of N,N-diacetyl-methylene-diformamide 102 g. of methylene-diformamide (1.0 mol) were boiled under reflux with an excess of acetic acid anhydride for 5 hours. Thereafter the acetic acid formed and the unreacted acetic acid anhydride were distilled off under vacuum and the oily residue immediately mixed with 100 ml. of ethanol. Upon cooling the N,N'-diacetylmethylene-diformamide crystallized out and was filtered off on a suction filter and washed with ethanol and ether and dried. The product was white in color and had a melting point of 8991 C. The yield was 82% of theory.

Analysis-Calculated for C H N O C, 45.16%; H, 5.42%; N, 15.05%. Found: C, 45.09%; H, 5.41%; N, 15.31%.

If the ethanol is not added immediately to the residue remaining after the acetic acid and the acetic acid anhydride has been distilled off, only a highly viscous brown oil is obtained and it is practically impossible to recover pure N,N-diacetyl-methylene-diformamide therefrom.

EXAMPLE 2 A cotton fabric which had been boiled in red wine for 1 hour and dried was washed three times for minutes at 60 C. in an aqueous bath which per liter contained the following:

Grams Lauryl sulfate 1.250 Sodium pyrophosphate 0.625 Sodium tripolyphosphate 0.625 Dry water glass 0.350 Sodium perborate 0.600

N,N-diacetyl-methylene-diformamide 0.725

As a comparison the bleaching effect attained with the same washing composition under the same conditions except for the omission of the N,N-diacetyl-methylenediformamide was also investigated. The white content of the red wine stained fabric before washing was 20% when measured with a Zeiss-Elrepho-whiteness measurer against white standard 565 with filter 6. After washing in the unactivated bath the whiteness content was 30% whereas after washing in the activated bath according to the invention the whiteness content was 48.6%. The increase in whiteness effected by the activation according to the invention therefore was 18.6%.

N,N-dibenzoyl-methylene-diformamide has a meltingpoint of 137139 C. and is very slightly soluble in water and gives an increase of whiteness of 10%; N,N'-dipropionyl-methylene-diformamide is a oily substance and easily soluble in water and gives an increase of whiteness of 2021%.

We claim:

1. In a process for the treatment of textile fibers with an aqueous bath containing an inorganic peroxidic bleaching agent, the step of incorporating in said bath 0.3 to 2 mols of an N,N'-diacyl-methylene-diformamide of the formula wherein R and R are carboxylic acid acyl groups having 1 to 12 carbon atoms per mol of active oxygen to activate said bleaching agent.

2. The process of claim 1 in which said bath contains between about 0.05 and 20 g. per liter of active oxygen.

3. The process of claim 2 in which said bleaching agent is sodium perborate and said activating compound is N,N-diacetyl-methylene-diformamide.

4. A solid stable activated bleaching composition consisting essentially of a solid inorganic peroxidic bleaching agent and about 0.3 to 2 mol of an N,N'-diacyl-methylene-diformamide of the formula wherein R and R are carboxylic acid acyl groups having 1 to 12 carbon atoms per mol of active oxygen in said peroxidic bleaching agent.

5. The bleaching composition of claim 4 in which said bleaching agent is sodium perborate and said diformamide is N.N'-diacetyl-methylene-diformamide.

References Cited UNITED STATES PATENTS 3,163,606 12/1964 Viveen et a1 252-99 X 3,177,148 4/1965 Bright et al. 252186 X LEON D. ROSDOL, Primary Examiner.

I. GLUCK, Assistant Examiner.

US. Cl. X.R. 252186, 95, 99 

